As a satirist once observed about an American vice president, it's hard to play second fiddle when you don't even have a bow.

The Constitution just doesn't give vice presidents much to do except wait around for something unfortunate to happen. Not all VPs have minded much: One had enough spare time to run a saloon. Others devoted themselves to pastimes like writing history books, dreaming about getting a law degree, and bashing the guy in the White House.

Things have changed. When Joe Biden and Paul Ryan meet in a debate on Thursday, they'll be vying for a position that's become vastly more vital.

A: For most of our history, up until recently, Vice President John Nance Garner hit the nail on the head.

But the trajectory of the office has been in a positive direction. Since 1977, the beginning of the Mondale vice presidency, it has really been a serious office. All of the vice presidents from Mondale on have been integral parts of the executive branch, right in the midst of White House decision-making.

Q: In the beginning, vice presidents were runners-up in elections and sometimes didn't actually like the presidents they served with. And then they began to be tapped to balance tickets, right?

A: The 19th-century vice presidents were really ticket-balancers who were chosen by party leaders. Sometimes they had resumes that were totally implausible.Chester Author was collector of customs at the port of New York, and I don't think anyone viewed him as presidential tinder. His job was to help carry New York.

Not long after the election, President Garfield was shot and lingered for 80 days. Then Arthur became president.

Andrew Johnson was a border state Democrat who was put on the ticket with Lincoln for political reasons. John Tyler had nothing in common with the policies of the Harrison administration, which only lasted for a month.

Q: Yet all of these men landed in the White House after presidents died. When did the political system start taking the vice presidency seriously?

A: The system changed around 1940 when the president became more powerful, the national government looked to do more, and the presidential candidates began to take a role in selecting their running mates. From 1976 on, it became increasingly clear that it was good politics to chose someone who was a plausible successor.

Q: Who are some of your favorite obscure vice presidents?

A: Garret Hobart, an unlikely guy who was McKinley's first vice president, had been a New Jersey state legislator. At that time, vice presidents were very peripheral to the business of government, but Hobart became very friendly with McKinley, and he played something of a role. He was an aberration. There's also Thomas Marshall, Woodrow Wilson's vice president, who compared being vice president to a catatonic state: "He cannot speak; he cannot move; he suffers no pain; and yet he is perfectly conscious of everything that is going on about him."

He also said "the only business of the vice-president is to ring the White House bell every morning and ask what is the state of health of the president." [Ironically, Marshall would be kept out of the loop when Wilson suffered a debilitating stroke and couldn't function as president.]

Q: I know from watching "24" on TV that the vice president does have an unusual power under the 25th Amendment: he or she can vote with the Cabinet to declare the president to be incapacitated and then take over, at least temporarily. Could this allow the VP to launch a coup?

A: You could imagine a situation when the vice president and Cabinet think the president is pursuing disastrous policies, and they declare him disabled. If there's a contest between the president on one side and the vice president and Cabinet on the other, ultimately the House and Senate have to decide the issue. Movies and novels have picked up on this theme.

Before him, vice presidents thought the way to become powerful would be to have the president delegate them turf.

He realized that presidents weren't going to give the vice president significant things to do. Presidents were more likely to give vice presidents menial things that would end up diminishing the vice president and eating up his time.

Mondale said he'd like to be an across-the-board senior adviser to the president, take on missions where the president thought he'd be helpful, and not have any ongoing program to run. That's what he and President Carter agreed to, and it worked well.

He created a model for other vice presidents.

Q: Who stands out among the least effective vice presidents?

A: Nelson Rockefeller, President Ford's vice president, was one of the most powerful people in the country -- governor of New York for four terms and leader of the eastern wing of the Republican Party.But the vice president role didn't fit him because he never figured out how to operate as vice president. In some ways he was obtuse, proposing things that were totally out of step with what President Ford was trying to do. He wasn't a very good follower.

And then there was Richard Nixon. At a press conference, President Eisenhower was asked about major ideas he'd heard from Nixon. "If you give me a week, I might think of one," he said. "I don't remember."

Q: Yikes. Well, at least Nixon didn't shoot anyone. Would you remind us who did?